The invention relates generally to detecting diseases of the gastrointestinal tract organs, and more particularly, relates to reagents such as polynucleotide sequences and the polypeptide sequences encoded thereby, as well as methods which utilize these sequences, which are useful for detecting, diagnosing, staging, monitoring, prognosticating, preventing or treating, or determining predisposition to diseases and conditions of the GI tract such as cancer.
The organs of the GI tract include the esophagus, stomach, small and large intestines, rectum and pancreas. Of the approximately 225,900 new cases of GI tract cancer projected for the United States during 1996, 131,200 will be due to colorectal cancer. Further, GI tract cancers will account for approximately 127,070 related deaths (American Cancer Society statistics). In addition to its high incidence, GI tract cancers can be extremely lethal; for example, greater than 97% of pancreatic cancer patients will die of the disease. H. J. Wanebo, et al., Cancer 78:580-91 (1996).
Generally, the early detection of GI tract cancers at a pre-invasive stage dramatically reduces disease-related mortality. However, only few GI tract cancers are detected at this stage. For example, only 37% of colorectal cancers are detected at this stage by screening for premalignant polyps which can be removed before they progress to cancer. The primary methods used for colorectal cancer screening are fecal occult blood testing (FOBT) and flexible sigmoidoscopy. A. M. Cohen et al. In: Cancer: Principles and Practice of Oncology, Fourth Edition, pp. 929-977, Philadelphia, Pa.: J/B. Lippincott Co. (1993). Although FOBT is noninvasive, simple and inexpensive, its sensitivity is low; for example, sensitivity for detecting colorectal cancer was only 26% in one study. D. A. Ahlquist et al., JAMA 269: 1262-1267 (1993). Further, although flexible sigmoidoscopy is highly sensitive for detecting early cancer and precursor polyps, it is invasive, costly, and too technically demanding to be used for routine screening. D. F. Ransohoff, et al., JAMA 269: 1278-1281 (1993). In addition, only eight percent (8%) of pancreatic cancers and eighteen percent (18%) of stomach cancers are detected at a pre-invasive stage (American Cancer Society statistics). Thus, the need exists for improved screening methods for detection of GI tract diseases such as cancer.
The standard procedures currently used for establishing a definitive diagnosis for a GI tract cancer include barium studies, endoscopy, biopsy and computed tomography (CT). These procedures are invasive and costly. Moreover, an erroneous diagnosis can result from any of these procedures due to technical reasons, the subjective interpretation of results, or lack of sensitivity of the procedure. M. F. Brennan, et al. In: Cancer: Principles and Practice of Oncology, Fourth Edition, pp. 849-882, Philadelphia, Pa.: J. B. Lippincott Co. (1993).
After the diagnosis of a particular GI tract cancer is confirmed, staging is performed to determine the anatomic extent of the disease. Staging is performed by a pathologist on tissue obtained by biopsy and/or surgery. Accurate staging is critical for predicting patient outcome and providing criteria for designing optimal therapy. Inaccurate staging can result in poor therapeutic decisions and is a major clinical problem in colorectal cancer. A need therefore exists for more sensitive diagnostic procedures for staging GI tract cancers.
While surgical resection of the affected organ is typical therapy for a majority of patients diagnosed with GI tract cancers, some patients undergo radiation and/or chemotherapy. All of these patients need to be monitored in order to evaluate their response to therapy and to detect persistent or recurrent disease and distant metastasis. A variety of markers including CEA and CA 19-9 can be assayed and the assay results used to monitor a patient""s progress in conjunction with radiological procedures and colonoscopy. E. L. Jacobs, Curr. Probl. Cancer 15 (6):299-350 (1991). These monitoring techniques, however, have failed to provide an accurate and effective means to monitor the progress of these patients.
Assays based upon the appearance of various disease markers in test samples such as blood, plasma or serum obtained by minimally invasive techniques, could provide low-cost and accurate information to aid the physician in diagnosing disease such as cancer, in selecting a therapy protocol, and in monitoring the success of the chosen therapy. Such markers have been placed into several categories. The first category contains those markers which are elevated in disease. Examples include human chorionic gonadotropin (hCG) which is elevated in testicular cancer and trophoblastic disease, and alpha fetoprotein (AFP) which is elevated in hepato-cellular carcinoma (HCC). E. L. Jacobs, supra. The second category includes qualitatively altered mRNA or protein markers in disease. Examples include mRNA splice variants of CD 44 in bladder cancer and mutations in p53 protein in lung and colorectal cancer. Y. Matsumura et al. Journal of Pathology 175(Suppl): 108A (1995); W. P. Bennett, Cancer Detection and Prevention 19 (6): 503-511 (1995). The third category includes those protein markers which are normally expressed in a specific tissue, organ or organ system but which appear in an inappropriate body compartment. For example, prostate specific antigen (PSA) is a normal protein which is secreted at high levels into the seminal fluid. PSA is present in very low levels in the blood of men with normal prostates but markedly elevated in the blood of patients with diseases of the prostate, including benign prostatic hyperplasia (BPH) and adenocarcinoma of the prostate. At high levels in the blood, PSA is a strong indicator of prostate disease. P. H. Lange et al., Urology 33 (6 Suppl): 13 (1989). Similarly, carcinoembryonic antigen (CEA) is a normal component of the inner lining of the colon which is present in blood at low levels in people without colon disease. E. L. Jacobs, supra. However, the CEA concentration is markedly elevated in the blood, plasma or serum of many patients diagnosed with colon disease including inflammatory bowel disease and adeno-carcinoma of the colon, and is used as an indicator of colorectal disease.
There are yet other examples of detecting disease markers in an inappropriate bodily compartment. In the case of metastatic cancer, the blood, bone marrow or lymph nodes may contain cells which have originated from the primary tumor and which may express mRNA or protein markers representative of the primary tumor. For example, CEA and PSA have been demonstrated immunohistochemically in lymph nodes or bone marrow of patients with metastatic colorectal cancer and prostate cancer, respectively. B. R. Davidson, et al., Cancer 65:967-970 (1990); J. L. Mansi, et al., J. Urol., 139:545-548 (1988). In addition, RT-PCR has detected CEA and PSA mRNAs at distant sites in patients with colon and prostate cancer, suggesting the presence of metastatic cells. M. Gerhard, et al., J. Clin. Oncol. 12:725-729 (1994); A. E. Katz, et al., Urology 43:765-775 (1994). Other compartments in which the inappropriate appearance of normal gene products may be indicative of disease include but are not limited to, whole blood, urine, saliva, and stool. Currently, no universally acceptable marker(s) exist(s) for the early detection of pancreatic, stomach, and esophageal cancers. Further, improved markers are needed to detect colorectal cancer.
It therefore would be advantageous to provide specific methods and reagents for detecting, diagnosing, staging, monitoring, prognosticating, preventing or treating, or determining predisposition to diseases and conditions associated with the GI tract or to indicate possible predisposition to these conditions. Such methods would include assaying a test sample for products of a gene which are overexpressed in GI tract diseases and conditions such as cancer. Such methods may also include assaying a test sample for products of a gene alteration associated with the GI tract disease or condition. Such methods may further include assaying a test sample for products of a gene whose distribution among the various tissues and compartments of the body have been altered by a GI tract-associated disease or condition such as cancer. Useful reagents include polynucleotide(s), or fragment(s) thereof which may be used in diagnostic methods such as reverse transcriptase-polymerase chain reaction (RT- PCR), PCR, or hybridization assays of mRNA extracted from biopsied tissue, blood or other test samples; polypeptides or proteins which are the translation products of such mRNAs; or antibodies directed against these proteins. Drug treatment or gene therapy for diseases or conditions of the GI tract then can be based on these identified gene sequences or their expressed proteins, and efficacy of any particular therapy can be monitored. Furthermore, it would be advantageous to have available alternative, non-surgical diagnostic methods capable of detecting early stage GI tract disease such as cancer.
The present invention provides a method of detecting a target CS198 polynucleotide in a test sample which comprises contacting the test sample with at least one CS198-specific polynucleotide and detecting the presence of the target CS198 polynucleotide in the test sample. The CS198-specific polynucleotide has at least 50% identity with a polynucleotide selected from the group consisting SEQUENCE ID NO 1, SEQUENCE ID NO 2, SEQUENCE ID NO 3, SEQUENCE ID NO 4, SEQUENCE ID NO 5, SEQUENCE ID NO 6, SEQUENCE ID NO 7, SEQUENCE ID NO 8, SEQUENCE ID NO 9, SEQUENCE ID NO 10, SEQUENCE ID NO 11, SEQUENCE ID NO 12, SEQUENCE ID NO 13, SEQUENCE ID NO 14, SEQUENCE ID NO 15, SEQUENCE ID NO 16, SEQUENCE ID NO 17, SEQUENCE ID NO 18, SEQUENCE ID NO 19, SEQUENCE ID NO 20, SEQUENCE ID NO 21, SEQUENCE ID NO 22, SEQUENCE ID NO 23, SEQUENCE ID NO 24, SEQUENCE ID NO 25, SEQUENCE ID NO 26, SEQUENCE ID NO 27 (xe2x80x9cSEQUENCE ID NOS 1-27xe2x80x9d), and fragments or complements thereof. Also, the CS198-specific polynucleotide may be attached to a solid phase prior to performing the method.
The present invention also provides a method for detecting CS198 mRNA in a test sample, which comprises performing reverse transcription (RT) with at least one primer in order to produce cDNA, amplifying the cDNA so obtained using CS198 oligonucleotides as sense and antisense primers to obtain CS198 amplicon, and detecting the presence of the CS198 amplicon as an indication of the presence of CS198 mRNA in the test sample, wherein the CS198 oligonucleotides have at least 50% identity to a sequence selected from the group consisting of SEQUENCE ID NOS 1-27, and fragments or complements thereof. Amplification can be performed by the polymerase chain reaction. Also, the test sample can be reacted with a solid phase prior to performing the method, prior to amplification or prior to detection. This reaction can be a direct or an indirect reaction. Further, the detection step can comprise utilizing a detectable label capable of generating a measurable signal. The detectable label can be attached to a solid phase.
The present invention further provides a method of detecting a target CS198 polynucleotide in a test sample suspected of containing target CS198 polynucleotides, which comprises (a) contacting the test sample with at least one CS198 oligonucleotide as a sense primer and at least one CS198 oligonucleotide as an anti-sense primer, and amplifying same to obtain a first stage reaction product; (b) contacting the first stage reaction product with at least one other CS198 oligonucleotide to obtain a second stage reaction product, with the proviso that the other CS198 oligonucleotide is located 3xe2x80x2 to the CS198 oligonucleotides utilized in step (a) and is complementary to the first stage reaction product; and (c) detecting the second stage reaction product as an indication of the presence of a target CS198 polynucleotide in the test sample. The CS198 oligonucleotides selected as reagents in the method have at least 50% identity to a sequence selected from the group consisting of SEQUENCE ID NOS 1-27, and fragments or complements thereof. Amplification may be performed by the polymerase chain reaction. The test sample can be reacted either directly or indirectly with a solid phase prior to performing the method, or prior to amplification, or prior to detection. The detection step also comprises utilizing a detectable label capable of generating a measurable signal; further, the detectable label can be attached to a solid phase. Test kits useful for detecting target CS198 polynucleotides in a test sample are also provided which comprise a container containing at least one CS198-specific polynucleotide selected from the group consisting of SEQUENCE ID NOS 1-27, and fragments or complements thereof. These test kits further comprise containers with tools useful for collecting test samples (such as, for example, blood, urine, saliva and stool). Such tools include lancets and absorbent paper or cloth for collecting and stabilizing blood; swabs for collecting and stabilizing saliva; and cups for collecting and stabilizing urine or stool samples. Collection materials, such as papers, cloths, swabs, cups, and the like, may optionally be treated to avoid denaturation or irreversible adsorption of the sample. The collection materials also may be treated with or contain preservatives, stabilizers or antimicrobial agents to help maintain the integrity of the specimens.
The present invention also provides a purified polynucleotide or fragment thereof derived from a CS198 gene. The purified polynucleotide is capable of selectively hybridizing to the nucleic acid of the CS198 gene, or a complement thereof. The polynucleotide has at least 50% identity with a polynucleotide selected from the group consisting of (a) SEQUENCE ID NOS 7-13 and complements thereof, (b) SEQUENCE ID NOS 15-26 and complements thereof, and (c) fragments of SEQUENCE ID NOS 7-26. Further, the purified polynucleotide can be produced by recombinant and/or synthetic techniques. The purified recombinant polynucleotide can be contained within a recombinant vector. The invention further comprises a host cell transfected with the recombinant vector.
The present invention further provides a recombinant expression system comprising a nucleic acid sequence that includes an open reading frame derived from CS198. The nucleic acid sequence has at least 50% identity with a sequence selected from the group consisting of SEQUENCE ID NOS 1-27, and fragments or complements thereof. The nucleic acid sequence is operably linked to a control sequence compatible with a desired host. Also provided is a cell transfected with this recombinant expression system.
The present invention also provides a polypeptide encoded by CS198. The polypeptide can be produced by recombinant technology, provided in purified form, or produced by synthetic techniques. The polypeptide comprises an amino acid sequence which has at least 50% identity with an amino acid sequence selected from the group consisting of (a) SEQUENCE ID NOS 43-47, and (b) fragments of SEQUENCE ID NOS 42-47.
Also provided is an antibody which specifically binds to at least one CS198 epitope. The antibody can be a polyclonal or monoclonal antibody. The epitope is derived from an amino acid sequence selected from the group consisting of SEQUENCE ID NOS 42-47, and fragments thereof. Assay kits for determining the presence of CS198 antigen or anti-CS198 antibody in a test sample are also included. In one embodiment, the assay kits comprise a container containing at least one CS198 polypeptide having at least 50% identity with an amino acid sequence selected from the group consisting of SEQUENCE ID NOS 42-47, and fragments thereof. Further, the test kit can comprise a container with tools useful for collecting test samples (such as blood, urine, saliva, and stool). Such tools include lancets and absorbent paper or cloth for collecting and stabilizing blood; swabs for collecting and stabilizing saliva; and cups for collecting and stabilizing urine or stool samples. Collection materials, such as papers, cloths, swabs, cups, and the like, may optionally be treated to avoid denaturation or irreversible adsorption of the sample. These collection materials also may be treated with or contain preservatives, stabilizers or antimicrobial agents to help maintain the integrity of the specimens. Also, the polypeptide can be attached to a solid phase.
Another assay kit for determining the presence of CS198 antigen or anti- CS198 antibody in a test sample comprises a container containing an antibody which specifically binds to a CS198 antigen, wherein the CS198 antigen comprises at least one CS198-encoded epitope. The CS198 antigen has at least about 60% sequence similarity to a sequence of a CS198-encoded antigen selected from the group consisting of SEQUENCE ID NOS 42-47, and fragments thereof. These test kits can further comprise containers with tools useful for collecting test samples (such as blood, urine, saliva, and stool). Such tools include lancets and absorbent paper or cloth for collecting and stabilizing blood; swabs for collecting and stabilizing saliva; cups for collecting and stabilizing urine or stool samples. Collection materials, such as papers, cloths, swabs, cups and the like, may optionally be treated to avoid denaturation or irreversible adsorption of the sample. These collection materials also may be treated with, or contain, preservatives, stabilizers or antimicrobial agents to help maintain the integrity of the specimens. The antibody can be attached to a solid phase.
A method for producing a polypeptide which contains at least one epitope of CS198 is provided, which method comprises incubating host cells transfected with an expression vector. This vector comprises a polynucleotide sequence encoding a polypeptide, wherein the polypeptide comprises an amino acid sequence having at least 50% identity with a CS198 amino acid sequence selected from the group consisting of SEQUENCE ID NOS 42-47, and fragments thereof.
A method for detecting CS198 antigen in a test sample suspected of containing CS198 antigen also is provided. The method comprises contacting the test sample with an antibody or fragment thereof which specifically binds to at least one epitope of CS198 antigen, for a time and under conditions sufficient for the formation of antibody/antigen complexes; and detecting the presence of such complexes containing the antibody as an indication of the presence of CS198 antigen in the test sample. The antibody can be attached to a solid phase and may be either a monoclonal or polyclonal antibody. Furthermore, the antibody specifically binds to at least one CS198 antigen selected from the group consisting of SEQUENCE ID NOS 42-47, and fragments thereof.
Another method is provided which detects antibodies which specifically bind to CS198 antigen in a test sample suspected of containing these antibodies. The method comprises contacting the test sample with a polypeptide which contains at least one CS198 epitope, wherein the CS198 epitope comprises an amino acid sequence having at least 50% identity with an amino acid sequence encoded by a CS198 polynucleotide, or a fragment thereof. Contacting is carried out for a time and under conditions sufficient to allow antigen/antibody complexes to form. The method further entails detecting complexes which contain the polypeptide. The polypeptide can be attached to a solid phase. Further, the polypeptide can be a recombinant protein or a synthetic peptide having at least 50% identity with an amino acid sequence selected from the group consisting of SEQUENCE ID NOS 42-47, and fragments thereof.
The present invention provides a cell transfected with a CS198 nucleic acid sequence that encodes at least one epitope of a CS198 antigen, or fragment thereof. The nucleic acid sequence is selected from the group consisting of SEQUENCE ID NOS 1-27, and fragments or complements thereof.
A method for producing antibodies to CS198 antigen also is provided, which method comprises administering to an individual an isolated immunogenic polypeptide or fragment thereof, wherein the isolated immunogenic polypeptide comprises at least one CS198 epitope. The immunogenic polypeptide is administered to the individual in an amount sufficient to produce an immune response. The isolated, immunogenic polypeptide comprises an amino acid sequence selected from the group consisting of SEQUENCE ID NOS 42-47, and fragments thereof.
Another method for producing antibodies which specifically bind to CS198 antigen is disclosed, which method comprises administering to a mammal a plasmid comprising a nucleic acid sequence which encodes at least one CS198 epitope derived from an amino acid sequence selected from the group consisting of SEQUENCE ID NOS 42-47, and fragments thereof. The plasmid is administered in an amount such that the plasmid is taken up by cells in the individual and expressed at levels sufficient to produce an immune response.
Also provided is a composition of matter that comprises a CS198 polynucleotide of at least about 10-12 nucleotides having at least 50% identity with a polynucleotide selected from the group consisting of (a) SEQUENCE ID NOS 7-13 and complements thereof, (b) SEQUENCE ID NOS 15-26 and complements thereof, and (c) fragments of SEQUENCE ID NOS 7-26. The CS198 polynucleotide encodes an amino acid sequence having at least one CS198 epitope. Another composition of matter provided by the present invention comprises a polypeptide with at least one CS198 epitope of about 8-10 amino acids. The polypeptide comprises an amino acid sequence having at least 50% identity with an amino acid sequence selected from the group consisting of (a) SEQUENCE ID NOS 43-47, and (b) fragments of SEQUENCE ID NOS 42-47. Also provided is a gene, or a fragment thereof, coding for a CS198 polypeptide having at least 50% identity with SEQUENCE ID NO 47; and a gene, or a fragment thereof, comprising DNA having at least 50% identity with SEQUENCE ID NO 26.